Really depends on the variety of carrot. Some of the main crop might not be ready until the autumn. Intermediate sooner and there are early varieties just like potatoes. I would not want to grow carrots in a container but if you feel that you want to give it another try in the future then the stump-rooted varieties like Chantenay would be a fair choice.

The roots swell later in the year if it is a late variety. the leaves send nutrients down to the tap root which swell forming the carrot that we eat.

It's still a young'un--it needs at least a dozen more leaves before it will even think about swelling up. In my experience, carrot foliage can get up to 50 cm tall before they are ready for harvest, except for the minis, such as 'Tonda di Parigi' or 'Little Finger'.

Hello

I am by no means an expert like the others here but have grown carrots a few times now in pots and have been generally successful.
As you have found they have very tiny seeds, which makes it difficult to space them out. They also seem to take ages to grow. It is far too early to expect them in June though the foliage is well developed.
They will be ready to pull up once you start to see the 'shoulders' appearing above the soil.
Hope you get a fine crop when the time comes!

Joan Airey